1. Field of the Invention
The present invention relates to a hydraulic system for a heavy equipment option which is capable of implementing a certain work by switching an option apparatus using a conventional straight traveling control valve when an option apparatus (referred to a braker) is additionally engaged to a small size excavator, and in particular to a hydraulic system for a heavy equipment option which is capable of controlling an operation oil which is supplied to an option apparatus by a switching apparatus switched together with a straight traveling control valve in a state that a design of a control valve assembly which controls an operation oil supplied to a traveling motor or a work apparatus in the case that an option apparatus is additionally engaged to a small size excavator of a crawler type.
2. Description of the Background Art
As shown in FIG. 1, a conventional hydraulic system of a heavy equipment includes a first control valve C1 which is switched by a pilot signal pressure Pi from a pilot pump(not shown) and controls an operation oil supplied from a first hydraulic pump P1 to a right side traveling motor(not shown) or a work apparatus, a second control valve C2 which is switched by a pilot signal pressure Pi and controls an operation oil from a second hydraulic pump P2 to a work apparatus(not shown), a third control valve C3 which is switched by a pilot signal pressure Pi and controls an operation oil from a third hydraulic pump P3 to a left traveling motor or a work apparatus, and a straight traveling control valve C4 which is switched by a straight traveling pilot signal pressure and combines the operation oils from the second and third hydraulic pumps P2 and P3 and straight-travels an equipment.
At this time, an operation oil from the first hydraulic pump p1 is drained to a hydraulic tank T1, and an operation oil from the second and third hydraulic pumps P2 and P3 is drained to the hydraulic tank T2 or T3.
However, in the case that an operation is implemented by an operation oil from the third hydraulic pump P3 by additionally engaging an option apparatus to a small excavator to which a conventional hydraulic system is adapted, since an additional switching apparatus capable of supplying an operation oil to an additional option apparatus is attached to a front or rear portion of the straight traveling control valve C4 or a design of a control valve structure should be changed, a size of a corresponding part is increased, and a work process is added, so that a fabrication cost is increased.
In addition, in order to engage a control valve assembly having a large outer size to a small size excavator, a substantial space is required, and a workability that a large size control valve assembly is engaged to a small space of a small size excavator is decreased.